Last modified: 2013-12-05 15:14:06 UTC

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Bug 29153 - Pages loading without formatting too often
Pages loading without formatting too often
Status: RESOLVED WORKSFORME
Product: MediaWiki
Classification: Unclassified
General/Unknown (Other open bugs)
unspecified
All All
: Normal normal with 2 votes (vote)
: ---
Assigned To: Asher Feldman
:
: 29214 (view as bug list)
Depends on:
Blocks: gadgets-2.0
  Show dependency treegraph
 
Reported: 2011-05-26 17:49 UTC by Helder
Modified: 2013-12-05 15:14 UTC (History)
10 users (show)

See Also:
Web browser: ---
Mobile Platform: ---
Assignee Huggle Beta Tester: ---


Attachments
Screenshot (104.12 KB, image/png)
2011-05-26 17:56 UTC, Helder
Details
The second random example. (190.83 KB, image/png)
2011-05-26 17:58 UTC, Helder
Details
Screenshot of the "ALL" tab (135.73 KB, image/png)
2011-06-01 12:54 UTC, Helder
Details
Screenshot of Firebug's "CSS" tab (119.85 KB, image/png)
2011-06-01 12:54 UTC, Helder
Details
Firebug - ALL (124.69 KB, application/octet-stream)
2011-06-01 13:00 UTC, Helder
Details
Firebug - CSS (136.40 KB, image/png)
2011-06-01 13:01 UTC, Helder
Details
Detailed screenshots (783.02 KB, application/zip)
2011-06-20 23:58 UTC, Helder
Details
Detailed screenshots (part2) (561.86 KB, application/zip)
2011-06-20 23:59 UTC, Helder
Details
Screenshot of MW Code Review without CSS on non-secure server (132.33 KB, image/png)
2011-07-02 13:21 UTC, Helder
Details
Error console on Google Chrome (71.25 KB, image/png)
2011-11-23 21:17 UTC, Helder
Details
Network tab on Google Chrome (100.46 KB, image/png)
2011-11-23 21:17 UTC, Helder
Details
Headers on Network tab on Google Chrome (129.57 KB, image/png)
2011-11-23 21:18 UTC, Helder
Details
Headers on Network tab on Google Chrome, after disabling all gadgets and cleared user scripts (119.04 KB, image/png)
2011-11-23 21:20 UTC, Helder
Details
On this, the CSS was loaded but there was an error in a JS request (117.47 KB, image/png)
2011-11-23 21:23 UTC, Helder
Details
Metawiki - Google Chrome - Network and error console (107.42 KB, image/png)
2011-11-24 19:38 UTC, Helder
Details
Metawiki - Google Chrome - Headers and console (140.86 KB, image/png)
2011-11-24 19:41 UTC, Helder
Details
Metawiki - Google Chrome - No Response, No Preview and no Cookies (87.09 KB, image/png)
2011-11-24 19:43 UTC, Helder
Details

Description Helder 2011-05-26 17:49:38 UTC
Occasionally the wiki pages are displayed without formatting. It seems that for some reason the CSS in not loaded.

Usually it is enough to refresh the cache by means of SHIFT+reload, but this has become necessary too often, so there seems to be something wrong. Besides, sometimes even if I refresh the current page, the problem happens again after I go to another page, making it necessary to clear the cache almost every page load.

At the moment I'm using Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.16) Gecko/20110430 Iceweasel/3.5.16 (like Firefox/3.5.16), and I am logged in on secure server.
Comment 1 Helder 2011-05-26 17:56:26 UTC
Created attachment 8586 [details]
Screenshot

I've just clicked on
https://secure.wikimedia.org/wikipedia/en/wiki/Special:Random

and got redirected to
https://secure.wikimedia.org/wikipedia/en/wiki/Badia_%28Castiglione_del_Lago%29
and there was no formatting.

The problem was fixed after I pressed CTRL+SHIFT+R. I tried
https://secure.wikimedia.org/wikipedia/en/wiki/Special:Random

again and got
https://secure.wikimedia.org/wikipedia/en/wiki/Manny_Acta

without the formatting and needed to prees CTRL+SHIFT+R again.
Comment 2 Helder 2011-05-26 17:58:13 UTC
Created attachment 8587 [details]
The second random example.
Comment 3 Helder 2011-05-26 18:12:35 UTC
I've tried the Epiphany browser, version 2.30.6, but wasn't able to reproduce the bug (or wasn't persistent enough ;-)

But on Iceweasel the problem happened also in the insecure server:
http://en.wikipedia.org/wiki/Special:Random
redirected to
http://en.wikipedia.org/wiki/Antelothanasis
and the formatting was missing.
Comment 4 Bawolff (Brian Wolff) 2011-05-26 18:17:24 UTC
Possibly related or dupe of bug 28857 (or potentially a totally separate issue).
Comment 5 Helder 2011-05-26 18:29:57 UTC
(In reply to comment #4)
> Possibly related or dupe of bug 28857 (or potentially a totally separate
> issue).

Hmm... Or maybe this is the same as bug 28714?
Comment 6 Bawolff (Brian Wolff) 2011-05-26 18:35:38 UTC
Honestly, all three could be the same issue, its hard to know if it is until the underlying cause is figured out.
Comment 7 Roan Kattouw 2011-05-26 19:11:31 UTC
It would be helpful if you could:
* install Firebug
* make sure Firebug is always enabled for secure.wikimedia.org (generally it's enough to open Firebug on a secure.wm.o page, then minimize it, it should remember your choice)
* enable the Net panel (again, Firebug should remember this choice)
* when this bug happens again, take a screenshot of the Net panel (of both the "All" and "CSS" tabs)
Comment 8 Mark A. Hershberger 2011-05-27 03:44:34 UTC
Roan, thanks for your debugging tips!  I've been running into this,
too.  Now, all I have to remember is the screenshot bit.
Comment 9 Helder 2011-06-01 12:54:24 UTC
Created attachment 8608 [details]
Screenshot of the "ALL" tab

(In reply to comment #7)
> * when this bug happens again, take a screenshot of the Net panel (of both the
> "All" and "CSS" tabs)

Here you are!
Comment 10 Helder 2011-06-01 12:54:55 UTC
Created attachment 8609 [details]
Screenshot of Firebug's "CSS" tab
Comment 11 Helder 2011-06-01 12:56:27 UTC
(In reply to comment #10)
> Created attachment 8609 [details]
> Screenshot of the "ALL" tab

Copy paste fail... I meant 'Screenshot of the "CSS" tab'.
Comment 12 Helder 2011-06-01 13:00:40 UTC
Created attachment 8610 [details]
Firebug - ALL

A second example, from article [[5 Canum Venaticorum]]
Comment 13 Helder 2011-06-01 13:01:18 UTC
Created attachment 8611 [details]
Firebug - CSS
Comment 14 Helder 2011-06-01 13:39:30 UTC
For the record: although the example above were from en.wp, I've also noticed it on other projects as well (e.g. pt.wp)
Comment 15 Roan Kattouw 2011-06-01 18:07:38 UTC
The screenshots of the CSS tab have the first entry expanded. Was there only one entry or were there more?

Also, the second page has half-completed styling, which is very weird. Are there any errors in the console tab?
Comment 16 Helder 2011-06-01 19:25:13 UTC
(In reply to comment #15)
> The screenshots of the CSS tab have the first entry expanded. Was there only
> one entry or were there more?
There was only one, so I expanded that entry to give more detailed info.

> Also, the second page has half-completed styling, which is very weird. Are
> there any errors in the console tab?

Not that I remember. But I'll know for sure when it happens again =)
Comment 17 Mark A. Hershberger 2011-06-02 01:52:18 UTC
(In reply to comment #14)
> For the record: although the example above were from en.wp, I've also noticed
> it on other projects as well (e.g. pt.wp)

Are you able to reproduce this problem fairly reliably?  If so, how reliably?  Within 5 minutes?

If you are able to reproduce this, would you be willing to do a screen-sharing session with a developer so that we can get this tracked down?
Comment 18 Helder 2011-06-02 03:57:57 UTC
(In reply to comment #17)
> (In reply to comment #14)
> > For the record: although the example above were from en.wp, I've also noticed
> > it on other projects as well (e.g. pt.wp)
> 
> Are you able to reproduce this problem fairly reliably?  If so, how reliably? 
> Within 5 minutes?

Since Roan suggested the use of Firebug, it only happened again yesterday. But in that occasion I was able to reproduce it at least once every 10 minutes (and some times on two or three consecutive page loads).

> If you are able to reproduce this, would you be willing to do a screen-sharing
> session with a developer so that we can get this tracked down?

Could I poke someone on IRC (who?) about this when I have access to the lab where I usually noticing the problem?
Comment 19 Helder 2011-06-02 18:04:46 UTC
(In reply to comment #16)
> (In reply to comment #15)
> > Also, the second page has half-completed styling, which is very weird. Are
> > there any errors in the console tab?
> 
> Not that I remember. But I'll know for sure when it happens again =)

Indeed. There was no errors in the console.

Right now, after I went to [[Special:PrefixIndex/Foo]] on the secure server, I was able to repeat the following at least 3 times in a row, being logged into my account:
* Typing some other name instead of "Foo" in the box entitled "Display pages with prefix:" and pressing ENTER
* The page was loaded without formatting (as in the previous screenshots)
* Pressing CTRL+SHIFT+R or SHIFT+Reload
* The page was loaded correctly, with all the usual formatting

To be sure it wasn't because of some JS, CSS or Gadget enabled in my user account, I logged out and was the steps above were still reproducible for 10 times or more.

While I was doing that, I noticed that in Firebug, in the cookie data displayed after expanding the list items (as in http://bug-attachment.wikimedia.org/attachment.cgi?id=8611) the value of "Cookie" included "enwikiUserName" even after I had logged out. I wasn't sure that it was supposed to be there for unlogged users, so I selected "Clear Recent History" in the browser, trying to clear everything. After this, I wasn't able to reproduce the bug anymore.

The browser used during these tests was the same as in the comment 1 (except that on this computer it is set to "pt-BR" instead of "en-US").
Comment 20 Brion Vibber 2011-06-02 18:19:53 UTC
Hmm... what's up with the Cache-Control line?

In the screenshots (both bad & good) we see:

  Cache-Control: public, max-age=2592000, s-maxage=2592000

on my own requests I see a much shorter user-facing timeout:

  Cache-Control: public, max-age=300, s-maxage=300

If there's some funky cache thing going on it might be keeping bad data around much longer than expected?
Comment 21 Roan Kattouw 2011-06-02 21:27:10 UTC
(In reply to comment #20)
> Hmm... what's up with the Cache-Control line?
> 
> In the screenshots (both bad & good) we see:
> 
>   Cache-Control: public, max-age=2592000, s-maxage=2592000
> 
> on my own requests I see a much shorter user-facing timeout:
> 
>   Cache-Control: public, max-age=300, s-maxage=300
> 
> If there's some funky cache thing going on it might be keeping bad data around
> much longer than expected?
Are you sure you're comparing apples with apples? load.php requests that set the &version= parameter have the long timeout, and requests without a version have the short timeout. The latter is used for the startup module that contains the last-modified timestamps for all the other modules.
Comment 22 Mark A. Hershberger 2011-06-03 20:45:58 UTC
*** Bug 29214 has been marked as a duplicate of this bug. ***
Comment 23 Krinkle 2011-06-13 19:29:07 UTC
During the RL2.0 sprint we'll look a this, no promises but a reminder.

Blocking bug 29272.
Comment 24 Mark A. Hershberger 2011-06-14 00:49:43 UTC
mybugs.mail@gmail.com has provided a screenshot which shows a load.php url supplying only 478 bytes of information (see http://bug-attachment.wikimedia.org/attachment.cgi?id=8608).  If you see that again, it would be helpful to know what those 478 bytes were. Probably a warning?

For purposes of others watching this bug, the RL2.0 sprint is during July 2011 -- IOW one month from now.  Please continue to supply information here.
Comment 25 Helder 2011-06-20 23:58:43 UTC
Created attachment 8686 [details]
Detailed screenshots

The problem happened today again and I've attached screenshots of the detailed info about each item displayed on Firebug.
Comment 26 Helder 2011-06-20 23:59:06 UTC
Created attachment 8687 [details]
Detailed screenshots (part2)
Comment 27 Helder 2011-06-21 00:00:21 UTC
PS: The CSS tab was empty.
Comment 28 Mark A. Hershberger 2011-06-22 15:54:17 UTC
(In reply to comment #27)
> PS: The CSS tab was empty.

Unless I'm mistaken, I don't see any CSS files being requested.  Which seems odd.
Comment 29 Bawolff (Brian Wolff) 2011-06-22 17:00:34 UTC
(In reply to comment #28)
> (In reply to comment #27)
> > PS: The CSS tab was empty.
> 
> Unless I'm mistaken, I don't see any CSS files being requested.  Which seems
> odd.

Not necessarily. CSS files are usually cached heavily. On a normal page view (not a hard refresh), its not unusual to not need any of the css files.
Comment 30 Mark A. Hershberger 2011-06-22 20:07:53 UTC
> Not necessarily. CSS files are usually cached heavily. On a normal page view
> (not a hard refresh), its not unusual to not need any of the css
> files.

Which makes sense if this is the first time this page was viewed.  But
if it wasn't the first time, then those additional images shouldn't
have been fetched.

And, if it was already fetched, then the CSS tab should not have been
empty, right?

Or, if the prior fetch of CSS returned an empty document, then the
styling problem should remain until a force-refresh wass done, at
least, which matches the symptoms in Comment #0.

(Sorry for being a pedant, but I'm just trying to track down all
details of this onerous issue.)
Comment 31 Bawolff (Brian Wolff) 2011-06-23 02:31:32 UTC
Well the images vary between every page. The CSS can be cached from previous pages on the wiki, where all the images might be new because they're only on a single page, so this could be the first time those images are seen. Since this page was loaded after a hit to [[special:random]]. Its quite probable that this is the first time that page was viewed.

>Or, if the prior fetch of CSS returned an empty document, then the
>styling problem should remain until a force-refresh wass done, at
>least, which matches the symptoms in Comment #0.

yep. So perhaps the css just did not get loaded(?).

Other weird things, is that the the wmf button at the bottom of the page did not appear to be in the browser cache (no if-modified-since header so not in browser cache. no pragma:no cache header so request wasn't from a hard refresh. Would be consistent with firebug's disable browser cache option, but then the css should not be cached either).  If any css was cached, one would expect other long cached resources to also be cached. The one JS file that was loaded was one that should be cached for a longish time, but the other js files that are normally cached for a short period of time were not loaded.

So yes, I think you're right in that the css was not simply just cached (although the evidence for that is kind of iffy), looks more like it just wasn't loaded, but I have no idea how that could happen.
Comment 32 MZMcBride 2011-06-23 02:50:57 UTC
I think sometimes logging/sampling the web server requests can be helpful in analyzing problems like this. Is that an option here? Could requests to bits.wikimedia.org be sampled and then check how many of them are either a 0 byte response length or return an HTTP code other than 200?

It's still a bit unclear to me how widespread this problem is (or if it's even a problem). I occasionally get pages with no CSS or limited CSS, but it could be Chrome being annoying or my ISP or whatever else. From some in-browser testing during times when bits.wikimedia.org wasn't returning the appropriate CSS, it seems it instead returns either a blank page or an error code of some kind (I can't remember which). If the incidence of these could be measured, I think it might be helpful.
Comment 33 Mark A. Hershberger 2011-06-24 14:33:19 UTC
(In reply to comment #32)
> Could requests to
> bits.wikimedia.org be sampled and then check how many of them are either a 0
> byte response length or return an HTTP code other than 200?

Asher did some testing for stuff like this yesterday (404s+5xx) but adding 0 length would be good.  He said that what he had wasn't scalable yet.  I'll ask him if he can look at this some more.

> It's still a bit unclear to me how widespread this problem is (or if it's even
> a problem). I occasionally get pages with no CSS or limited CSS, but it could
> be Chrome being annoying or my ISP or whatever else.

Reports started showing up after we pushed ResourceLoader and it isn't a browser-specific problem since you're seeing it on Chrome and I see it on FireFox.  I doubt it is an ISP issue since the reports really started showing up after RL.  (Although, it is possible that they started showing up because now we think it is RL and we're just seeing a pile-on effect).

> If the incidence of these could be measured, I
> think it might be helpful.

Thank you for this suggestion.  I'll see if I can make it happen.
Comment 34 Asher Feldman 2011-06-24 19:03:32 UTC
The log analysis stuff I was working on was just for the squids so isn't applicable for secure bits requests.  I'll look into what we currently collect and see if there's enough to analyze, or if we need to turn on additional logging.
Comment 35 Asher Feldman 2011-06-27 22:39:09 UTC
Is it safe to say that this bug is primarily just related to https wikipedia access via secure.wikimedia.org?  I did see a comment about being able to reproduce the case via the http wikipedia.org but that seemed like an edge case related to a forked browser.
Comment 36 MZMcBride 2011-06-27 22:46:23 UTC
I've had pages return that look pretty much identical to the attached screenshot (<http://bug-attachment.wikimedia.org/attachment.cgi?id=8608>), but it's always been on http, never on https. I don't generally use https with Wikimedia wikis.
Comment 37 Asher Feldman 2011-06-27 22:51:38 UTC
Do we have any firebugs style resource load screenshots for this issue occurring via http?
Comment 38 Asher Feldman 2011-06-29 00:40:41 UTC
All of the example screenshots point to the secure gateway which is a single proxy server that doesn't handle some relative urls correctly.  It's being replaced with a much better solution that will enable https:// on actual wiki domain names.  Once that has been rolled out, it may solve this.

Any issue with css not loading from standard http wikis is likely a different issue but this ticket doesn't currently contain information that would help track it down.  Screenshoots similar to what has been attached for the secure.wikimedia.org issue would be helpful.
Comment 39 Bawolff (Brian Wolff) 2011-07-01 01:40:40 UTC
btw, do we have any logging for times when a non-existant module is requested (how often does it happen, which modules)? [Today I accidentally screwed up something on my local install which caused all the modules to be missing, which caused very similar symptoms as to whats being described here. It's probably coincidence they have similar symptoms, but it'd perhaps be a good idea to have information on if there are requests for missing modules]


For the relative urls are screwed up on secure - If that was causing problems wouldn't we be seeing 404's in the firebug screenshots (or at least screwed up request urls)?
Comment 40 Helder 2011-07-02 13:21:19 UTC
Created attachment 8736 [details]
Screenshot of MW Code Review without CSS on non-secure server

The bug just happened on MW.org when I was using Google Chrome, not logged, and using http.

Unfortunately I wasn't expecting it so when I pressed CTRL+SHIFT+J and went to the resources tab it displayed
  "No requests captured. Reload the page to see detailed information on the network activity."
(and when I reloaded the page it was displayed correctly)

Anyway, when the error occurred this time, the error console displayed
  "Failed to load resource".
Comment 41 MZMcBride 2011-07-21 00:54:38 UTC
I was visiting <http://www.mediawiki.org/wiki/Thread:Talk:Article_feedback/%D0%A4%D0%B8%D0%BB%D1%8C%D0%BC%D1%8B_%D0%BE%D0%BD%D0%BB%D0%B0%D0%B9%D0%BD?useskin=vector> just now and it loaded without styles. I investigated a bit and it was a getting a 404 from this URL: <http://bits.wikimedia.org/www.mediawiki.org/load.php?debug=false&lang=en&modules=site&only=styles&skin=vector>.

It was a standard "Not Found" 404 error message. I tried a few more times via the browser and curl and then it fixed itself, returning the appropriate CSS.

I don't think this is a issue related to the secure server. What's the status of logging frequency of HTTP codes other than 200?
Comment 42 Asher Feldman 2011-07-21 02:31:55 UTC
We now have a build of varnish 3.0 with a udp logging daemon that should be transparently compatible with our squid log collection infrastructure.  There are some VCL language changes in 3.0 and the bits/geo-ip vcl needs porting and testing before bits will be upgraded.  Mobile is getting varnish 3.0 first in the next week or two, then bits testing can begin. 

I performed a days worth of local sampling internally on one of the bits varnish servers last week however and found rare 503's caused by first byte timeouts from the backend apache's (1:1000000 requests or less.) I filtered out 404's however due to the huge amount of legitimate ones being served due to malformed requests, bots, and broken bits installed on some wikis.  I did just catch an interesting 404 on sq67 however, that was requested by Firefox 3.6.18

The RxURL listed is :  http://bits.wikimedia.org/en.wikipedia.org/load.php?debug=false&lang=en&modules=mediawiki%21legacy%21commonPrint%7Cmediawiki%21legacy%21shared%7Cskins%21vector&only=styles&skin=vector

That's a good URL except, the RxURL field doesn't contain the protocol or host portion of the url - this means it was a request for : http://bits.wikimedia.org/http://bits.wikimedia.org/en.wikipedia.org/load.php?debug=false&lang=en&modules=mediawiki%21legacy%21commonPrint%7Cmediawiki%21legacy%21shared%7Cskins%21vector&only=styles&skin=vector

Not something I'd expect a 3.6 build of firefox to do - this could be an occasional bug in page rendering but it could also be due to factors outside of our control.  I'm going to dig around further to see if I can find a load.php 404's that's been properly requested.

 3724 SessionOpen  c 209.226.31.161 50441 :80
 3724 ReqStart     c 209.226.31.161 50441 3365871486
 3724 RxRequest    c GET
 3724 RxURL        c http://bits.wikimedia.org/en.wikipedia.org/load.php?debug=false&lang=en&modules=mediawiki%21legacy%21commonPrint%7Cmediawiki%21legacy%21shared%7Cskins%21vector&only=styles&skin=vector
 3724 RxProtocol   c HTTP/1.1
 3724 RxHeader     c Host: bits.wikimedia.org
 3724 RxHeader     c User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.18) Gecko/20110614 Firefox/3.6.18
 3724 RxHeader     c Accept: text/css,*/*;q=0.1
 3724 RxHeader     c Accept-Language: en-us,en;q=0.5
 3724 RxHeader     c Accept-Encoding: gzip,deflate
 3724 RxHeader     c Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
 3724 RxHeader     c Keep-Alive: 115
 3724 RxHeader     c Proxy-Connection: keep-alive
 3724 RxHeader     c Referer: http://en.wikipedia.org/wiki/James_I_of_England
 3724 VCL_call     c recv lookup
 3724 VCL_call     c hash hash
 3724 VCL_call     c miss fetch
 3724 Backend      c 3775 appservers srv249
 3724 TTL          c 3365871486 RFC 120 1311214434 0 0 0 0
 3724 VCL_call     c fetch deliver
 3724 ObjProtocol  c HTTP/1.1
 3724 ObjStatus    c 404
 3724 ObjResponse  c Not Found
 3724 ObjHeader    c Date: Thu, 21 Jul 2011 02:13:54 GMT
 3724 ObjHeader    c Server: Apache
 3724 ObjHeader    c Content-Type: text/html; charset=iso-8859-1
 3724 VCL_call     c deliver deliver
 3724 TxProtocol   c HTTP/1.1
 3724 TxStatus     c 404
 3724 TxResponse   c Not Found
 3724 TxHeader     c Server: Apache
 3724 TxHeader     c Content-Type: text/html; charset=iso-8859-1
 3724 TxHeader     c Content-Length: 342
 3724 TxHeader     c Date: Thu, 21 Jul 2011 02:13:54 GMT
 3724 TxHeader     c X-Varnish: 3365871486
 3724 TxHeader     c Age: 0
 3724 TxHeader     c Via: 1.1 varnish
 3724 TxHeader     c Connection: keep-alive
 3724 Length       c 342
 3724 ReqEnd       c 3365871486 1311214434.264867306 1311214434.265794277 0.000029802 0.000903606 0.000023365
Comment 43 Sumana Harihareswara 2011-10-31 14:35:26 UTC
Can the original bug reporter still reproduce this problem?  Since we've now deployed SSL and MediaWiki 1.18 on all WMF wikis (so one doesn't need to use the secure.wikimedia.org server anymore), I'm curious to know whether it's recurring.
Comment 44 Helder 2011-11-23 21:17:08 UTC
Created attachment 9532 [details]
Error console on Google Chrome

I noticed the problem several times today, when accessing pages such as
http://en.wikipedia.org/wiki/Bregman_divergence
on Google Chrome 15.0.874.121. Some times using CTRL+SHIFT+R or SHIFT+Reload didn't restore the formatting.

But the problem still doesn't happens consistently. I was logged in when It happened in the page above. I tryied to replicate it without success:
* Being logged off
* Using Iceweasel/3.5.16

Maybe it was something related to the fact that MediaWiki:Common.css was changed recently:
http://en.wikipedia.org/w/index.php?diff=462098416&oldid=461932865
Comment 45 Helder 2011-11-23 21:17:57 UTC
Created attachment 9533 [details]
Network tab on Google Chrome
Comment 46 Helder 2011-11-23 21:18:47 UTC
Created attachment 9534 [details]
Headers on Network tab on Google Chrome
Comment 47 Helder 2011-11-23 21:20:13 UTC
Created attachment 9535 [details]
Headers on Network tab on Google Chrome, after disabling all gadgets and cleared user scripts
Comment 48 Helder 2011-11-23 21:23:34 UTC
Created attachment 9536 [details]
On this, the CSS was loaded but there was an error in a JS request
Comment 49 Roan Kattouw 2011-11-24 10:31:19 UTC
(In reply to comment #47)
> Created attachment 9535 [details]
> Headers on Network tab on Google Chrome, after disabling all gadgets and
> cleared user scripts
This one is very interesting: supposedly Chrome got a 403 Forbidden response (!!). If you ever get a 403 again, please include the full headers *and the content*. I can see from the Content-Length header that the response is 117 bytes, but I don't see the actual body of the 403 response in your screenshots. This should be in the "Response" tab.

The other failures are really weird. Attachment 9532 [details] shows a failure for both flaggedrevs CSS and the jquery&mediawiki JS request (obviously if that one fails, any other JS that does load explodes immediately). Attachment 9533 [details] shows a different page load where only the flaggedrevs CSS failed to load; according to the net panel it failed to load, but when you look at the details in attachment 9534 [details] the response from the server was a 304 (which means Chrome must've had a cached version handy, and the server is telling it that that cached version is still good; so how can it fail to load?). Attachment 9535 [details] makes sense to me (403 from the server, don't know how that would happen, but Chrome's reaction to it makes sense), but attachment 9536 [details] is even weirder: the WikiEditor request fails to load, but it's a cached 200 response?!

This might be related to http://stackoverflow.com/questions/6559825/corrupt-google-chrome-cache (doubtful, though, as I haven't seen any weird Range headers in your screenshot), or to another bug that might exist in Chrome where it sends a no-caching header (Cache-Control: max-age=0 in one of your screenshots, Cache-Control: no-cache & Pragma: no-cache in the other) 
along with an If-Modified-Since header; I'm not sure if that's legal and how servers are supposed to respond to that, but we respond to it with a 304 (because of the IMS) and I guess that might confuse Chrome.
Comment 50 Liangent 2011-11-24 10:39:00 UTC
I also see this randomly (missing of Common.css). Browsers used include Iceweasel on PC and Opera Mini on cellphone IIRC. I cannot reproduce it somehow so it's not easy for me to provide debug info.
Comment 51 Helder 2011-11-24 19:38:57 UTC
Created attachment 9545 [details]
Metawiki - Google Chrome - Network and error console

The problem happened on Meta-wiki, while I was logged in. Here are the screenshots.
Comment 52 Helder 2011-11-24 19:41:10 UTC
Created attachment 9546 [details]
Metawiki - Google Chrome - Headers and console
Comment 53 Helder 2011-11-24 19:43:40 UTC
Created attachment 9547 [details]
Metawiki - Google Chrome - No Response, No Preview and no Cookies

This screenshot shows that there was no response. I've checked also preview and cookies tabs and they were blank too.
Comment 54 Asher Feldman 2011-11-30 01:36:05 UTC
I just deployed a change to our bits varnish servers that has the following effect:

- if a backend request fails with a 5xx error, varnish will retry up to 4 times

- if content has changed but the backend is taking too long to generate a new version, the expired content will still be served for up to 20 minutes

I'm hopeful that this will largely address the issue.  Please continue to provide feedback on any future occurrences.
Comment 55 Liangent 2011-12-01 16:07:49 UTC
I met this again and caught related request&response data, it's a 403 Forbidden:

== Location ==

http://bits.wikimedia.org/zh.wikipedia.org/load.php?debug=false&lang=zh-cn&modules=ext.wikihiero%7Cmediawiki.legacy.commonPrint%2Cshared%7Cskins.vector&only=styles&skin=vector&*

== Request Headers ==

Host: bits.wikimedia.org

User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1 Iceweasel/7.0.1

Accept: text/css,*/*;q=0.1

Accept-Language: en-us,en;q=0.5

Accept-Encoding: gzip, deflate

Accept-Charset: UTF-8,*

Referer: http://zh.wikipedia.org/wiki/Template:Subst_after/doc

DNT: 1

Connection: keep-alive

== Response Headers ==

Server: Apache

X-Powered-By: PHP/5.3.2-2wm1

X-Content-Type-Options: nosniff

Cache-Control: no-cache

Content-Encoding: gzip

Vary: Accept-Encoding

X-Vary-Options: Accept-Encoding;list-contains=gzip

Content-Type: text/html

Content-Length: 117

Accept-Ranges: bytes

Date: Thu, 01 Dec 2011 16:01:42 GMT

X-Varnish: 1642196564 1641737561

Age: 45

Via: 1.1 varnish

X-Cache: hit (37)

== Response Body ==

Scripts should use an informative User-Agent string with contact information, or they may be IP-blocked without notice.
Comment 56 Asher Feldman 2011-12-01 19:11:28 UTC
This is a different case than at least some of the previous ones (based on content-length + non-empty response body) but this is a great find.  

In this case, a request for the given url is hitting bits without a user-agent, mediawiki returns a 403 for that reason, and varnish is caching the 403.  I should be able to fix this case today.
Comment 57 Asher Feldman 2011-12-01 20:45:28 UTC
The fix for not caching 403's has been pushed to production (though if any of these are currently cached, they'll have to expire.)
Comment 58 Bawolff (Brian Wolff) 2011-12-02 01:13:15 UTC
(In reply to comment #56)
> This is a different case than at least some of the previous ones (based on
> content-length + non-empty response body) but this is a great find.  
> 
> In this case, a request for the given url is hitting bits without a user-agent,
> mediawiki returns a 403 for that reason, and varnish is caching the 403.  I
> should be able to fix this case today.

I always thought that user-agent 403's were given by the squids/varnish servers themselves not MediaWiki (Although I suppose it could still be caching its own response).
Comment 59 Asher Feldman 2011-12-02 01:38:56 UTC
The no-ua 403 does come from mediawiki, but it's a wmf specific customization:

wmf-config/checkers.php:                die( "Scripts should use an informative User-Agent string with contact information, or they may be IP-blocked without notice.\n" );
Comment 60 Liangent 2011-12-05 06:17:45 UTC
I saw this again but didn't log any debug info this time. However I guess all cache must have gone away.(In reply to comment #57)
> The fix for not caching 403's has been pushed to production (though if any of
> these are currently cached, they'll have to expire.)

I saw this again but didn't log any debug info this time. However I guess all cache must have gone away.
Comment 61 Helder 2012-03-16 22:58:46 UTC
I think I found something which may be related to (or be) the cause of these errors in the computers I use. Everything seems to work fine until I get near my disk quota on these linux machines. After that, the frequency of the errors increase a lot.
Once I clear my browser's navigation data, or delete some files, it seems to stop failing and works until I reach my quota again.
Comment 62 Bawolff (Brian Wolff) 2012-03-17 02:00:03 UTC
(In reply to comment #61)
> I think I found something which may be related to (or be) the cause of these
> errors in the computers I use. Everything seems to work fine until I get near
> my disk quota on these linux machines. After that, the frequency of the errors
> increase a lot.
> Once I clear my browser's navigation data, or delete some files, it seems to
> stop failing and works until I reach my quota again.

Hmm interesting. Possible explanations I could see for this is:
*Firefox is very broken when its low on disk space
*Firefox stops caching things when low on disk space, resulting in getting things directly from the server more often, and hence errors happening more regularly (This assumes instances of css failing are the result of requests that fail in a way that isn't cached on the client side)
Comment 63 Liangent 2012-03-17 10:23:04 UTC
I don't see such errors these days.
Comment 64 Helder 2012-03-17 11:07:38 UTC
(In reply to comment #62)
> Hmm interesting. Possible explanations I could see for this is:
> *Firefox ...
For the record: when I tested what I said in comment 61 I was using Google Chrome.
Comment 65 Andre Klapper 2013-12-04 16:25:32 UTC
Helder: Is this still a problem nowadays?
Comment 66 Helder 2013-12-04 16:59:21 UTC
If I try to use one of those computer where there is the disk quota, the errors increase in frequency as Google Chrome use more and more space...

(and this happens quite often, as a simple search confirms:
https://www.google.com.br/search?q=%22google+chrome%22+folder+too+big
)
Comment 67 Andre Klapper 2013-12-05 15:14:06 UTC
User quota is nothing that could be fixed by MediaWiki...

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